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GCSE Maths: Tree Diagrams

Practise GCSE Maths tree diagrams for combined events, with and without replacement, and conditional probability. AQA, Edexcel, OCR and Eduqas.

ProbabilityFoundation & HigherAQA · Edexcel · OCR · Eduqas

What you need to know

The concepts examiners test on tree diagrams, and what each one is really asking.

Drawing tree diagrams
Multiplying along branches
Adding outcomes between branches
With and without replacement
Conditional probability from tree diagrams

Where marks get lost

The exam technique that separates a correct method from a correct answer.

  • Probabilities along each set of branches must sum to 1
  • Multiply along branches for "and" (both events occur)
  • Add results of different branches for "or" (either path leads to the outcome)

Tree Diagrams questions students ask

What is the difference between with and without replacement?

With replacement: the item is put back, so probabilities stay the same for each draw. Without replacement: the item is not returned, so the total decreases and probabilities change.